lOMoAR cPSD| 65448581
NSG 4100 Exam 2 Study Notes (PDF) | 2026 Pituitary
Disorders and More
🧠 Memory Trick:
● DI (Diabetes Insipidus): D ry I nside (High urine output, dehydration).
● SIADH: S oaked I nside (Low urine output, water intoxication).
Diabetes Insipidus (DI)
Definition
● Most common disorder of the posterior lobe of the pituitary gland characterized by a deficiency of
ADH (vasopressin).
🩺 Pathophysiology & Classification
● Pathophysiology: Decreased ADH → inability to concentrate urine → excretion of large volumes of
dilute urine.
● Causes:
○ Head trauma / Brain tumor.
○ Surgical ablation or irradiation of pituitary.
○ CNS infections (meningitis/encephalitis).
○ Failure of renal tubules to respond to ADH ( Nephrogenic DI ) - related to Hypokalemia,
Hypercalcemia, or Lithium use .
📝 Clinical Manifestations
● Polyuria: Enormous daily output (> 250 mL/hr).
○ Urine is dilute with Specific Gravity 1.001 – 1.005 .
● Polydipsia: Intense thirst (drinking 2–20 L/day).
● Craving for cold water.
● Dehydration signs: Poor skin turgor, dry mucous membranes.
● Hypernatremia: Serum Sodium > 145 mEq/L (due to water loss).
● Hypotension, Tachycardia (hypovolemic shock risk).
🧪 Diagnostics & Labs
Test Result in DI
, lOMoAR cPSD| 65448581
Urine Specific Gravity Low (1.001 – 1.005)
Urine Osmolality Low (< 200 mOsm/kg)
Serum Sodium High (> 145 mEq/L)
Serum Osmolality High (> 300 mOsm/kg)
⭐ Fluid Deprivation Test (High Yield)
● Purpose: To diagnose DI and differentiate neurogenic vs. nephrogenic causes.
● Procedure: Fluids withheld for 8-12 hours or until 3-5% body weight is lost.
● 🚨 SAFETY ALERT - STOP THE TEST IF:
○ Patient exhibits tachycardia .
○ Excessive weight loss occurs. ○
Hypotension develops.
● Trial of Desmopressin: Given during test. If urine osmolality increases, it is Central (Neurogenic)
DI . If no response, it is Nephrogenic DI .
💊 Medical Management & Medications
1. Replace ADH:
○ Desmopressin (DDAVP): Synthetic vasopressin (Intranasal spray, PO, IV).
■ Mechanism: Increases water absorption in kidneys.
■ Indication: Neurogenic DI.
■ Nursing: Monitor for water intoxication (headache, confusion).
2. Thiazide Diuretics: Used for Nephrogenic DI (potentiates action of vasopressin).
3. Prostaglandin Inhibitors: Ibuprofen/Indomethacin (helps nephrogenic DI).
👩⚕️ Nursing Interventions & Priority Actions
● 🚨 Priority: Maintain fluid volume status.
● Assessment:
○ Accurate I&O (Critical).
○ Daily Weights (Same scale, same time).
○ Monitor for S/S of Hypernatremia (restlessness, weakness, dry tongue).
● Hydration: encourage fluids; replace fluids IV (hypotonic saline usually) if unable to drink. ● Patient
Education:
○ Wear medical alert bracelet.
, lOMoAR cPSD| 65448581
○ Carry medication information at all times.
Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
Definition
● Excessive secretion of ADH leading to water retention and dilutional hyponatremia.
🩺 Pathophysiology
● Excess ADH → Kidneys reabsorb water → Intravascular fluid volume increases → Dilutional
Hyponatremia and decreased serum osmolality.
● Non-Endocrine Causes:
○ Bronchogenic Carcinoma (Small Cell Lung Cancer) - Most common cause .
○ Pneumonia, Pneumothorax.
○ Head injury / Brain tumors.
○ Meds: Vincristine, Phenothiazines, TCAs, Thiazides, Nicotine.
📝 Clinical Manifestations
● Early signs: Thirst (paradoxical), Dyspnea on exertion, Fatigue.
● Fluid Volume Excess: Weight gain WITHOUT peripheral edema (water is retained inside
cells/vasculature, not interstitial).
● Hyponatremia Symptoms:
○ Na+ < 120 mEq/L: Vomiting, abdominal cramps, muscle twitching.
○🚨 Cerebral Edema (Na+ < 115): Confusion, lethargy, seizures, coma, Cheyne-Stokes
respirations.
🧪 Diagnostics & Labs
Test Result in SIADH
Urine Specific Gravity High (> 1.030)
Urine Sodium High (Concentrated)
Serum Sodium Low (< 135 mEq/L)
NSG 4100 Exam 2 Study Notes (PDF) | 2026 Pituitary
Disorders and More
🧠 Memory Trick:
● DI (Diabetes Insipidus): D ry I nside (High urine output, dehydration).
● SIADH: S oaked I nside (Low urine output, water intoxication).
Diabetes Insipidus (DI)
Definition
● Most common disorder of the posterior lobe of the pituitary gland characterized by a deficiency of
ADH (vasopressin).
🩺 Pathophysiology & Classification
● Pathophysiology: Decreased ADH → inability to concentrate urine → excretion of large volumes of
dilute urine.
● Causes:
○ Head trauma / Brain tumor.
○ Surgical ablation or irradiation of pituitary.
○ CNS infections (meningitis/encephalitis).
○ Failure of renal tubules to respond to ADH ( Nephrogenic DI ) - related to Hypokalemia,
Hypercalcemia, or Lithium use .
📝 Clinical Manifestations
● Polyuria: Enormous daily output (> 250 mL/hr).
○ Urine is dilute with Specific Gravity 1.001 – 1.005 .
● Polydipsia: Intense thirst (drinking 2–20 L/day).
● Craving for cold water.
● Dehydration signs: Poor skin turgor, dry mucous membranes.
● Hypernatremia: Serum Sodium > 145 mEq/L (due to water loss).
● Hypotension, Tachycardia (hypovolemic shock risk).
🧪 Diagnostics & Labs
Test Result in DI
, lOMoAR cPSD| 65448581
Urine Specific Gravity Low (1.001 – 1.005)
Urine Osmolality Low (< 200 mOsm/kg)
Serum Sodium High (> 145 mEq/L)
Serum Osmolality High (> 300 mOsm/kg)
⭐ Fluid Deprivation Test (High Yield)
● Purpose: To diagnose DI and differentiate neurogenic vs. nephrogenic causes.
● Procedure: Fluids withheld for 8-12 hours or until 3-5% body weight is lost.
● 🚨 SAFETY ALERT - STOP THE TEST IF:
○ Patient exhibits tachycardia .
○ Excessive weight loss occurs. ○
Hypotension develops.
● Trial of Desmopressin: Given during test. If urine osmolality increases, it is Central (Neurogenic)
DI . If no response, it is Nephrogenic DI .
💊 Medical Management & Medications
1. Replace ADH:
○ Desmopressin (DDAVP): Synthetic vasopressin (Intranasal spray, PO, IV).
■ Mechanism: Increases water absorption in kidneys.
■ Indication: Neurogenic DI.
■ Nursing: Monitor for water intoxication (headache, confusion).
2. Thiazide Diuretics: Used for Nephrogenic DI (potentiates action of vasopressin).
3. Prostaglandin Inhibitors: Ibuprofen/Indomethacin (helps nephrogenic DI).
👩⚕️ Nursing Interventions & Priority Actions
● 🚨 Priority: Maintain fluid volume status.
● Assessment:
○ Accurate I&O (Critical).
○ Daily Weights (Same scale, same time).
○ Monitor for S/S of Hypernatremia (restlessness, weakness, dry tongue).
● Hydration: encourage fluids; replace fluids IV (hypotonic saline usually) if unable to drink. ● Patient
Education:
○ Wear medical alert bracelet.
, lOMoAR cPSD| 65448581
○ Carry medication information at all times.
Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
Definition
● Excessive secretion of ADH leading to water retention and dilutional hyponatremia.
🩺 Pathophysiology
● Excess ADH → Kidneys reabsorb water → Intravascular fluid volume increases → Dilutional
Hyponatremia and decreased serum osmolality.
● Non-Endocrine Causes:
○ Bronchogenic Carcinoma (Small Cell Lung Cancer) - Most common cause .
○ Pneumonia, Pneumothorax.
○ Head injury / Brain tumors.
○ Meds: Vincristine, Phenothiazines, TCAs, Thiazides, Nicotine.
📝 Clinical Manifestations
● Early signs: Thirst (paradoxical), Dyspnea on exertion, Fatigue.
● Fluid Volume Excess: Weight gain WITHOUT peripheral edema (water is retained inside
cells/vasculature, not interstitial).
● Hyponatremia Symptoms:
○ Na+ < 120 mEq/L: Vomiting, abdominal cramps, muscle twitching.
○🚨 Cerebral Edema (Na+ < 115): Confusion, lethargy, seizures, coma, Cheyne-Stokes
respirations.
🧪 Diagnostics & Labs
Test Result in SIADH
Urine Specific Gravity High (> 1.030)
Urine Sodium High (Concentrated)
Serum Sodium Low (< 135 mEq/L)
